Great quake in Sumatra

A magnitude 8.4 earthquake struck offshore Sumatra about 6 p.m. local time Wednesday. Tsunamis were reported in Padang and elsewhere along the western shore of the Indonesian island. It was a classic subduction-related thrust event that occurred about 30 kilometers deep, directly on a line with the chain of small islands off Sumatra in the Indian Ocean. Follow the scientific information on the USGS's special page for this event.

And 12 hours later a magnitude 7.8 event, perhaps an aftershock or perhaps a triggered event, occurred about 200 kilometers to the north. A tsunami watch was announced and, judging from the location and shallow depth, this event may well have pushed waves onto the neighboring islands.